Process for refining copper-nickel matte.



UNITED STATES PATENT OFFICE.

NOAK VICTOR HYBINETTE, OF WESTFIELD, NEW JERSEY. PROCESS FOR REFININGCOPPER NICKEL MATTE.

Specification of Letters Patent.

Patented Nov. 28, 1905.

Application filed November 25,1904. Serial No. 23%,180.

To all whom it may concern.

Be it known that I, N OAK VIoToR HYBINETTE,

a citizen of the United States of America, andv a resident of Westfield,county of Union, and State of New Jersey, have invented certain new anduseful Improvements in Processes for Refining Copper-Nickel Matte, ofwhich the following is a specification The raw material for my processis-a copper-nickel sulfid produced by roasting and smelting of ordinarycoppernickel ores. Thisraw material, generally called concentratedmatte, contains about twenty-iive per cent. sulfur and one-half percent. to five per cent. iron, the remainder being copper and nickel indiffering proportions, generally about thirty-five'to forty per cent: ofeach metal.

The first step in my process is now to grind and roast the matte. Theroasted material is leached with sulfuric acid until the material willno longer neutralize the acid. This step in'my process is not newinitself and is wellknown to those conversant with the metallurgy ofnickel. I prefer to grind the matte to a size passing through a screenwith thirty meshes to the inch. The roasting is started at a lowtemperature and gradually increased until the sulfur contents arebrought down to about one per cent. More or less copper and nickel willbe changed into sulfates; but such sulfur as is present as sulfates isnot detrimental; but after the material is leached with water there maystill be allowed to remain about one per cent. sulfur. When the materialis being leached with sulfuric acid, I take the precaution to use onlydilute acid, so that the amount of free acid in my solution will at notime be more than five to ten per cent. In this way it is possible toremove the bulk of the copper withoutat the same time dissolving muchnickel. My solution will contain one partnickel to aboutten parts ofcopper. If I do the leaching with stronger acid, the proportion ofnickel will be greater. The solution so prepared is crystallized andboiled down and again crystallized, and at each repeated crystallizationI receive crystals of commercially pure copper sulfate. Themother-liquor from such crystallization contains copper and nickel inabout equal parts. I concentrate it and boil it down to a solid mass ofco pper-nickel sulfates. Thematerial that has been leached containsabout fifty-five to sixty per cent. nickel and twelveto eighteen percent. copper and is subjected to the second operation in my process. Imix the material with sulfuric acid of about sixty per cent. free acidin such'quantity that there will be suflicient acid to form. sulfate ofcopper with a'llthe copper that is present. The mass is then slowlybrought up to a low red heat and roasted at that temperature for a shorttime. The reaction that takes place is that the free acid becomescombined with copper and nickel to sulfates of these metals; but sulfateof copper is preferably formed. When the material reaches a temperatureof about 800 centigrade, the sulfates begin to decompose; but thesulfate of copper is not affected in the same way'as the sulfate ofnickel, and the consequence is that when the sulfates are completelydecomposed, or nearly so, and the material drawn from the furnace andleached with weak sulfuric acid I again obtain a solution with about tenpartsof copper to one part of nickel and which upon crystallization willyield commercially pure sulfate of copper. The mother-liquor from thissecond leaching is of the same nature as that above referred to and isboiled down, giving more salts of about equal parts of copper andnickel.

This heating with sulfuric acid may be repeated, and after one or moresuch treatments I have a residue after leaching which contains aboutseventy per cent. nickel and three to five per cent. copper. The nextstep in my process is to mix this residue with hydrochloric acid or amixture of common salt or chlorid of sodium and sulfuric acid. Thematerial is again heated to a low red heat, and chlorids of nickel andcopper are formed. As, however, chlorid of nickel is far more readilydecomposed by heat than chlorid of copper. I can continue my roastingoperation to a point where a maximum of copper and a maxim um of nickelare present as chlorids. I then draw the material from the furnace andleach it with. water and weak acid, whereby I obtaina residue ofpractically pure nickel oxid with about one-half per cent. copper stillpresent. The treatment with hydrochloric acid may be repeated, in whichcase a still more pure nickel oxid is obtained, assaying aboutseventy-seven per cent. nickel and onetenth per cent. copper. Thischlor-idizing roasting of nickel oxidfor the sakegof removing smallpercentages of copper is not unlike the ordinary Henderson process forthe-extraction of copper from ores and is well known to those conversantwith metallurgy of nickel. The reactions that take place no pure saltscan be separated.

in my sulfuric-acid process are probably not corresponding to orcongruent with those of.

of nickel in the mixed oxids isnot in such excess as to protect the oxidof copper from the action of the acid. This point .is reached when thecopper percentage is down to twelve to fifteen per cent. It is lower themore copper was contained in the original material and the lower thetemperature of roasting. After this point no separation of copper byleaching is possible, and such material has heretofore been handled inthe very expensive way of completely dissolving the whole mass inhydrochloric acid and precipitating the metals separately from suchsolution. I have now found that if the material is heated in a furnacewith concentrated sulfuric acid large quantities of both copper andnickel form sulfates, but always so that a greater proportion of copperthan nickel is made soluble. This proportion is more favorable thehigher the copper contents are in the material. If, therefore, thepercentage of copper is as high as, say, eighteen per cent., I can drawthe material from the furnace at a point below red heat, where only thefree acid is driven off, and the solution with water will then containcopper and nickel in about equal quantities. When, however, the copperisdown to twelve per cent.- or below, I find that an undue proportion ofnickel is made soluble, and I do therefore raise the heat to apointwhere all or nearly all nickel sulfate is decomposed. At this pointthe copper is also made insoluble in water, but not in the same way asthe nickel, because it is again made soluble by very weak acid, and thesolution so obtained contains very little nickel. I have no theoreticalexplanation to offer for this process; but it is a fact that each timethe material is heated with sulfuric acid I can afterward extract aportion of the copper-with acid so weak that it would have no influenceon the material before said heating. This nickel oxid is refined tometallic nickel in one of the several ways now in use and well known tothose conversant with the art. Preferably I may smelt the oxid tometallic nickel anodes containing about ninety five per cent. nickel.'Such anodes are suitable for refining by ordinary electrolyticprocesses. This last leaching of chlorids leaves a solution from whichIt contains nickel and copper in about equal parts.

Each one of the three steps in my process has left a solution of mixedcopper and nickel salts. I prefer to heat these salts to astrong redheat, whereby all the nickel sulfate and chlorid are changed in oxid.leached with water and weak sulfuric acid, whereby copper sulfate isagain obtained, and the residue from the leaching is nickel oxid ofabout the same purity as that produced by the regular process.

It is evident that instead of heating with acid I may use its chemicalequivalent, such as sodium bisulfate, which upon heating will give offsulfuric acid, and instead of using hydrochloric acid I may use sodiumbisulfate and sodium chlorid, which upon heating will produce h ydrochioric acid.

The treatment which I have calledthe second step is naturally moreexpensive than the first, and there is no call for its use until thecopper contents are reduced to about twelve per cent, at which point theoperation called the first step refuses to work satisfactorily.Thissecond step gives less favorable results the lower the coppercontents are and has to be substituted by the treatment withhydrochloric acid when the percentage of copper is brought down to fiveto three per cent. This third step is not practical when the coppercontents are above three to five per cent.; but by combining the threesteps I can successfully treat all grades of material.

I do not intend'to make any claim to the first and third steps inthemselves. They have long been known to be well suitable for theseparation of copper; but as the first step becomes impractical when thecopper contents have been brought down to twelve per cent. and the thirdstep cannot very well be used until the copper is as low as three tofive per cent. it has been impossible to combine the two in a practicalprocess. I have now invented the process of separating copper fromnickel by heating with sulfuric acid and leaching with weak acid, aprocess which is well suited to'handle the material after the first stepis no longer useful and leave a product which can be convenientlytreated by chloridizing roasting.

There are many electrolytic copper-refineries which treat nickel-bearingcopper. These factories made as a by-product a mixed sulfate of aboutequal portions of nickel and copper. \Vith former processes this salthas to go through a long'and expensive separating process; but accordingto my invention these i-salts may be handled as the mother-liquor fromcrystallization of sulfate of copper, as

herein described.

WVha't I claim as my invention is 1. The process of separating copperfrom nickel in copper-nickel matte, consisting in first roasting thematte to oxids, then leaching with weak sulfuric acid, therebyextracting principally sulfate of copper, then heating This residueiswith sulfuric acid at least to a temperature where hydrous sulfates donot exist, leaching with weak sulfuric acid, thereby extractingprincipally sulfate of copper, then heat-' ing with hydrochloric acid toa temperature enough for partial decomposition of the anhydrouschloricls, leaching with weak acid and repeating the said beatings whennecessary thereby obtaining a nickel oxid, suitable for refining byordinary means.

2. The process of separating oxids of copper and nickel by heating withsulfuric acid at least to a temperature Where hydrous sulfates do notexist, leaching with weak sulfuric acid, thereby extracting principallysulfate of copper, then heating with hydrochloric acid to a temperaturehigh enough for partial decomposition of the anhydrous chlorids,leaching with Weak acid and repeating the said beatings when necessarythereby obtaining a nickel oxid, suitable for refining byordinary means.

3. In the process of separating oxids by heating with sulfuric acid andleaching with weak acid, the method of heating the material to at leastpartial decomposition of the anhydrous sizlfates and leaching with Weak'acid, thereby extracting copper oxid formed in said decompositionwithout extracting the nickel oxid formed at the same time.

Signed atNeW York this 22d day of November, 1904.

NOAK VICTOR HYBINETTE. Witnesses:

(J. SEDGWICK, J ,M. HOWARD.

